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unmtr
ultiplies a complex matrix by the complex unitary matrix Q determined by hetrd. This routine belongs to the oneapi::mkl::lapack namespace.
Description
The routine multiplies a complex matrix C by Q or QH, where Q is the unitary matrix Q formed by hetrd when reducing a complex Hermitian matrix A to tridiagonal form: A = Q*T*QH. Use this routine after a call to hetrd.
Depending on the parameters left_right and trans, the routine can form one of the matrix products Q*C, QH*C, C*Q, or C*QH (overwriting the result on C).
API
Syntax
namespace oneapi::mkl::lapack {
void unmtr(sycl::queue &queue,
mkl::side side,
mkl::uplo uplo,
mkl::transpose trans,
int64_t m,
int64_t n,
sycl::buffer<T> &a,
int64_t lda,
sycl::buffer<T> &tau,
sycl::buffer<T> &c,
int64_t ldc,
sycl::buffer<T> &scratchpad,
int64_t scratchpad_size)
}unmtr supports the following precisions and devices:
T |
Devices supported |
|---|---|
std::complex<float> |
CPU |
std::complex<double> |
CPU |
Input Parameters
In the descriptions below, r denotes the order of Q:
r = m |
if side = side::left |
r = n |
if side = side::right |
- queue
-
Device queue where calculations will be performed.
- side
-
Must be either side::left or side::right.
If side = side::left, Q or QT is applied to C from the left.
If side = side::right, Q or QT is applied to C from the right.
- uplo
-
Must be either uplo::upper or uplo::lower. Uses the same uplo as supplied to hetrd (USM Version).
- trans
-
Must be either transpose::nontrans or transpose::trans.
If trans = transpose::nontrans, the routine multiplies C by Q.
If trans = transpose::trans, the routine multiplies C by QT.
- m
-
The number of rows in the matrix C(m ≥ 0).
- n
-
The number of columns in the matrix C(n ≥ 0).
- a
-
Buffer holding array returned by hetrd (USM Version).
- lda
-
The leading dimension of a(lda ≥ max(1, r)).
- tau
-
Buffer holding tau returned by hetrd (USM Version). The dimension of tau must be at least max(1, r-1).
- c
-
Buffer holding the matrix C. The second dimension of c must be at least max(1, n).
- ldc
-
The leading dimension of c(ldc ≥ max(1, m)).
- scratchpad
-
Buffer holding scratchpad memory to be used by the routine for storing intermediate results.
- scratchpad_size
-
Size of scratchpad memory as a number of floating point elements of type T. Size should not be less than the value returned by the unmtr_scratchpad_size function.
Output Parameters
- c
-
Overwritten by the product Q*C, QT*C, C*Q, or C*QT (as specified by side and trans).
Exceptions
Exception |
Description |
|---|---|
mkl::lapack::exception |
This exception is thrown when problems occur during calculations. You can obtain the info code of the problem using the info() method of the exception object: If info = -i, the i-th parameter had an illegal value. If info is equal to the value passed as scratchpad size, and detail() returns non-zero, then the passed scratchpad has an insufficient size, and the required size should not be less than the value returned by the detail() method of the exception object. |